This invention relates to the conversion of chemical energy to electrical energy, and more particularly to a new and improved construction for lithium-iodine cells and method of making the same.
One area of use of the present invention is in providing electrical power safely to inaccessible devices in the human environment, for example to an implanted cardiac pacemaker, although the principles of the present invention can be variously applied. Several types of batteries for implantable cardiac pacemakers have been proposed, but heretofore all have certain limitations. Recently, a lithium-iodine cell has been proposed which advantageously has an open circuit voltage about twice that of the mercury cell, does not generate gas during operation, and has a non-corrosive electrolyte.
Several problems can arise in the manufacture or assembly of lithium-iodine cells. A cell has been proposed including a lithium anode and a cathode comprising a charge transfer complex of an organic component and iodine. Some charge transfer complexes while being highly desirable for cell operation are difficult and costly to produce. Other problems arise when the anode and cathodes are assembled, for example any air gaps remaining therebetween can, through lithium nitride formation, form an internal electrical short circuit in the cell, and if the cathode material does not completely contact the anode an abnormally high impedance can build up at the small remaining interface.